AB0809 INTERSTITIAL LUNG DISEASE SECONDARY TO ANTI SYNTHETASE SYNDROME AND SYSTEMIC SCLEROSIS: DIFFERENCES IN CHARACTERISTICS AND IMMUNOSUPPRESSIVE TREATMENT RESPONSE
Authors: T. Eviatar, O. Freund, T. Shalmon, S. Schneer, Y. Adir, O. Wand, D. Shitrit, O. Elkayam, A. Bar-Shai, A. Unterman
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Anti synthetase syndrome (ASS) is an inflammatory myositis with autoantibodies against one of the aminoacyl transfer RNA synthetase. Interstitial lung disease (ILD) is a main clinical feature which dictates the prognosis and treatment. Since there are no randomized controlled trials to guide therapy, treatment strategies are extrapolated from other connective tissue diseases-related-ILD (CTD-ILD), mainly systemic sclerosis (SSc). <h3>Objectives</h3> Our aim was to evaluate the effect of immunosuppressive treatment (IS) on ASS-related ILD, compared with SSc-related ILD. <h3>Methods</h3> A multicenter observational registry, including 45 patients with CTD-ILD (ASS (n=18) and SSc (n=27)) from 3 medical centers in Israel, between 2017-2021. During follow up, 12 patients did not receive any IS, while 17 patients started IS treatment shortly after the 1<sup>st</sup> visit and 16 after a period of follow up. We compared the <b>monthly</b> change in diffusion capacity for carbon monoxide (DLCO) and forced vital capacity (FVC) percent predicted between ASS and SSc. Further analysis included a comparison between non-IS and IS treated patients. Mann-Whitney test was used to compare medians, with a p value of &lt;0.05 considered significant. <h3>Results</h3> The mean±SD age was 62.9±10 and 31 (69%) were females. ILD as the presenting disease feature was more common in ASS, compared with SSc (61% vs. 11%, p&lt;0.001). DLCO% was lower at baseline among ASS patients (44 ±13 vs. 57 ±14, p=0.004), while other lung function measures were not significantly different (table 1). Overall, 32 patients (71%) received an IS therapy. As expected, glucocorticoid treatment was more prevalent in the ASS group (n=14) compared to the SSc group (n=8) (78% vs. 30%, p=0.002). The most prevalent non-steroidal IS was mycophenolate mofetil (MMF) (96%). Two ASS and one SSc received azathioprine. There was a trend towards a monthly improvement of DLCO% among treated patients with ASS compared with SSc (median change of 0.30 vs. -0.17 percentage points, p=0.053), while among non-IS treated patients there was no difference in the decline (-0.27 vs. -0.29, p=0.853) (figure 1). When comparing CTD-ILD treated with IS, with non-treated patients among patients with ASS, IS was associated with a monthly increase in DLCO% (0.3 vs. -0.27 without IS, p=0.001), and in SSc – a lower rate of decline (-0.17 vs. -0.29, p=0.041); However, the positive change of FVC% in both ASS (0.12 vs. 0.33, p=0.217) and SSc (-0.38 vs. 0, p=0.79) patients was not statistically significant. <h3>Conclusion</h3> Immunosuppressive therapy, and specifically MMF, was associated with an improvement in DLCO% in patients with ASS and lower rate of decline in SSc. ILD in the context of ASS may responds better to immunosuppressive treatment compared to ILD in SSc. These encouraging results need to be validated in larger scaled randomized prospective studies to assess the role of MMF in ILD related to ASS. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.